A Study on the Factors Affecting Customer Satisfaction with Institutional Foodservice during COVID-19

This study used a mixed-methods design combining qualitative and quantitative research to understand the factors affecting customer satisfaction with institutional foodservice during COVID-19. First, in-depth interviews and open coding were conducted with institutional foodservice users, and they indicated that harmonious menu composition, food taste, food temperature, close proximity to the restaurant, clean tableware, staff hygiene, hand sanitizer use, and table dividers were important concepts (qualities). Second, factors affecting customer satisfaction and dissatisfaction with institutional foodservice were analyzed using the Kano model, customer satisfaction coefficient, and importance–satisfaction analysis. The highest priorities derived from those analyses for improving the quality of institutional foodservice were harmonious menu composition and food temperature. This mixed-methods study is meaningful because it comprehensively analyzes the satisfaction factors important to customers of institutional foodservice, which have changed because of COVID-19. Therefore, these results will help to improve institutional foodservice and industrial development.


Introduction
Institutional foodservice provides meals to workers in corporate offices, factories, dormitories, training centers, and the like at workplace cafeterias (called staff cafeterias, staff canteens, employee canteens, staff restaurants, employee restaurants, etc.).
Institutional foodservice provides healthy, well-balanced food to workers [1,2]. Improvements in physical dining areas and the quality of employee meals increases employee satisfaction and financial performance [3,4]. Upon the introduction of institutional foodservice, productivity was improved [5], meal skipping was reduced [6], the nutritional quality of lunch was improved over a long period of time [7], and the salt content of lunch was reduced [8]. Institutional foodservice is thus an important research subject because it affects company productivity by supplying necessary nutrients to workers, which helps them maintain their health and increases work efficiency.
Institutional foodservices provide meals to many workers (i.e., customers) under established conditions and standards. Some customers are satisfied with the meal, some are dissatisfied, and some take them for granted or are indifferent. As factors of customer satisfaction with institutional foodservice, materials (location, cleanliness of dishes and cutlery, etc.), service (staff politeness, staff outfits, etc.), menu (taste and temperature of meals, variety of meals on the daily menu, etc.) [1]; variety of menu items, value for money [3]; clean and hygienic employee restaurant, various meals, delicious food [4]; and salt intake [7] have been used. As foodservice has developed, the requirements of customers who use institutional foodservice have become increasingly diverse, and in the

Research Design
This study analyzed customer satisfaction factors by taking a user-based approach and using an exploratory sequential mixed method [19,20].
The qualitative research method was used because it is suitable for collecting information about issues and problems in the field, focusing on the perspectives and views of various research participants, and understanding and interpreting in-depth phenomena and events experienced by research participants [21][22][23]. However, qualitative research is difficult to generalize. Therefore, the customer satisfaction factors of institutional foodservice were also comprehensively analyzed in quantitative research using data collected with a questionnaire. The research procedure is shown in Figure 1. difficult to generalize. Therefore, the customer satisfaction factors of institutional foodservice were also comprehensively analyzed in quantitative research using data collected with a questionnaire. The research procedure is shown in Figure 1. Study 1 was a qualitative research phase that used in-depth interviews with institutional foodservice customer to identify customer satisfaction factors and then derive quality factors for institutional foodservice derived from the qualitative research phase.
During the tool development phase, a questionnaire was written using the quality factors for institutional foodservice derived from the qualitative research phase.
Study 2 was a quantitative research phase. After analyzing the attributes of institutional food service quality using the Kano model, factors affecting customer satisfaction and dissatisfaction were identified using customer satisfaction coefficient CSC. In addition, improvement priorities for customer satisfaction were analyzed using an importance-satisfaction analysis (ISA).

Participants
This qualitative research was conducted from 8 September-13 October 2020. In this study, three adult participants who worked for a food manufacturing company, large mart, and bank, respectively, and had experience using institutional foodservices were selected as a purposive sample. Nine more people were then recruited using snowball sampling, a method of receiving recommendations from other study participants, for a total of 12 subjects.

Measure
The in-depth interview is a method of collecting data in field studies [24] through conversations with individuals or multiple research participants [25].
In this study, the 12 participants were asked to describe satisfactory or unsatisfactory experiences with institutional foodservice. At this time, a semi-structured interview method was used, and an interview guide was prepared to effectively direct the in-depth interviews. The interview guide contained questions about the reasons for using institutional foodservice, satisfactory and unsatisfactory aspects of using institutional foodservice, and the factors that should be considered to further develop institutional foodservice. The interview guide focused the interviews on the study's purpose and direction and thereby affected the expected results [26].
Open coding is the process of breaking down, examining, comparing, conceptual izing, and categorizing data by comparison [27,28]. In this study, repeated reading of the transcripts was used to derive concepts (qualities). Those qualities were then grouped by similarity, and category names were created for each category. At this time, the category names used words spoken by participants or words that researcher considered meaningful.
To increase the reliability and validity of this study, triangulation, member checking, and peer examination were conducted. As shown in Table 1, the professor and director Study 1 was a qualitative research phase that used in-depth interviews with institutional foodservice customer to identify customer satisfaction factors and then derive quality factors for institutional foodservice derived from the qualitative research phase.
During the tool development phase, a questionnaire was written using the quality factors for institutional foodservice derived from the qualitative research phase.
Study 2 was a quantitative research phase. After analyzing the attributes of institutional foodservice quality using the Kano model, factors affecting customer satisfaction and dissatisfaction were identified using customer satisfaction coefficient (CSC). In addition, improvement priorities for customer satisfaction were analyzed using an importancesatisfaction analysis (ISA).

Study 1 2.2.1. Participants
This qualitative research was conducted from 8 September-13 October 2020. In this study, three adult participants who worked for a food manufacturing company, large mart, and bank, respectively, and had experience using institutional foodservices were selected as a purposive sample. Nine more people were then recruited using snowball sampling, a method of receiving recommendations from other study participants, for a total of 12 subjects.

Measure
The in-depth interview is a method of collecting data in field studies [24] through conversations with individuals or multiple research participants [25].
In this study, the 12 participants were asked to describe satisfactory or unsatisfactory experiences with institutional foodservice. At this time, a semi-structured interview method was used, and an interview guide was prepared to effectively direct the in-depth interviews. The interview guide contained questions about the reasons for using institutional foodservice, satisfactory and unsatisfactory aspects of using institutional foodservice, and the factors that should be considered to further develop institutional foodservice. The interview guide focused the interviews on the study's purpose and direction and thereby affected the expected results [26].
Open coding is the process of breaking down, examining, comparing, conceptual izing, and categorizing data by comparison [27,28]. In this study, repeated reading of the transcripts was used to derive concepts (qualities). Those qualities were then grouped by similarity, and category names were created for each category. At this time, the category names used words spoken by participants or words that researcher considered meaningful.
To increase the reliability and validity of this study, triangulation, member checking, and peer examination were conducted. As shown in Table 1, the professor and director with experience in foodservice management and quality research conducted peer examinations, analyzed transcriptional data, and reviewed and revised the coding contents. In Study 1, a Kano model questionnaire and ISA questionnaire were constructed using 30 qualities of institutional foodservice derived from the in-depth interviews and open coding. The Kano model questionnaire paired a positive question and a negative question for each quality, as shown in Table 2. The ISA questionnaire asked about the importance of and satisfaction with each quality, as shown in Table 3. Questions to collect demographic and foodservice usage data were added.  This quantitative research was conducted from 18 November-28 December 2020. A survey participation notice was attached to the entrance of the workplace cafeteria of the food manufacturing company, automobile manufacturer, bank, and government office where the 12 participants of the qualitative research worked. In addition, a questionnaire was distributed to adult participants who had experience using institutional foodservice and expressed their intention to participate in this study, and participants were recruited using snowball sampling. The required number of participants was calculated using previous studies and G-Power programs. A total of 390 samples were calculated as necessary, but 487 people were recruited to allow for a dropout rate of 20%. Therefore, 487 production workers, service workers, office workers, professionals, and executives completed the offline survey.

Measure
To identify the attributes of institutional foodservice quality, a Kano evaluation table was used to classify each quality, i.e., to find the best attribute for each quality (Figure 2). A category strength of less than 6% was classified as a Combination [29]. Second, the factors affecting customer satisfaction were identified through the CSC, as shown in Figure 3, using the quality attributes classified through the Kano model.

Measure
To identify the attributes of institutional foodservice quality, a Kano evaluation table was used to classify each quality, i.e., to find the best attribute for each quality (Figure 2). A category strength of less than 6% was classified as a combination [29]. Second, the factors affecting customer satisfaction were identified through the CSC, as shown in Figure  3, using the quality attributes classified through the Kano model. Based on the two-factor theory [30], the Kano model classifies quality according to the degree to which a thing physically meets or does not meet the required standard in the objective aspect and the consumer's satisfaction or dissatisfaction with the thing in the subjective aspect [31,32]. The Kano model can thus identify factors that affect customer satisfaction or dissatisfaction and is used in various industries to identify customer needs for products and services and measure customer satisfaction. It is studied in various forms and integrated with other models to form complex models [33][34][35][36][37].
The factors affecting customer satisfaction were identified through the CSC, as shown in Figure 3, using the quality attributes classified through the Kano model [38]. Third, an ISA was conducted to identify the priorities institutional foodservice improvement. The ISA theory modifies the importance-performance analysis [39] to determine improvement priorities by considering satisfaction instead of performance. First,  Based on the two-factor theory [30], the Kano model classifies quality according to the degree to which a thing physically meets or does not meet the required standard in the objective aspect and the consumer's satisfaction or dissatisfaction with the thing in the subjective aspect [31,32]. The Kano model can thus identify factors that affect customer satisfaction or dissatisfaction and is used in various industries to identify customer needs for products and services and measure customer satisfaction. It is studied in various forms and integrated with other models to form complex models [33][34][35][36][37].
The factors affecting customer satisfaction were identified through the CSC, as shown in Figure 3, using the quality attributes classified through the Kano model [38]. Third, an ISA was conducted to identify the priorities institutional foodservice improvement. The ISA theory modifies the importance-performance analysis [39] to determine improvement priorities by considering satisfaction instead of performance. Based on the two-factor theory [30], the Kano model classifies quality according to the degree to which a thing physically meets or does not meet the required standard in the objective aspect and the consumer's satisfaction or dissatisfaction with the thing in the subjective aspect [31,32]. The Kano model can thus identify factors that affect customer satisfaction or dissatisfaction and is used in various industries to identify customer needs for products and services and measure customer satisfaction. It is studied in various forms and integrated with other models to form complex models [33][34][35][36][37].
The factors affecting customer satisfaction were identified through the CSC, as shown in Figure 3, using the quality attributes classified through the Kano model [38].
Third, an ISA was conducted to identify the priorities institutional foodservice improvement. The ISA theory modifies the importance-performance analysis [39] to determine improvement priorities by considering satisfaction instead of performance. First, participants completed the ISA questionnaire, which asked about the importance and satisfaction of various factors, and each response was scored and analyzed (very high = 5, high = 4, moderate = 3, low = 2, very low = 1).
The factors tested were divided into quadrants reflecting their importance for improvement: concentrate management here (highest priority), keep up the good work, low priority for managers, and possible overkill [40].
Fourth, a nominal scale was used for demographic questions and questions about institutional foodservice usage.
All data in this study were analyzed using SPSS 22 (Statistical Package for Social Sciences Version 22.0) and Excel 10.0, and the research methods used for each analysis are shown in Table 4.

Study 1
As shown in Table 5, in-depth interviews were conducted with 12 participants who use institutional foodservice, and open coding of their responses produced 30 qualities of interest, which were categorized into seven sub-categories and three categories, as shown in Table 6. The quality, sub-category, and category names of institutional foodservice features reflected terms used by the participants. Among the sub-categories of ingredients, hygiene, and facilities, the words 'corona', 'cleanliness', and 'safety' were mentioned frequently and grouped into a category named 'safety' [41]. Before performing this qualitative research, the quality factors for institutional foodservice reported in previous studies was examined. When the quality factors for institutional foodservice derived through the in-depth interviews and open coding in this study were compared with those reported in previous studies in Korea, most of the results were consistent, but 'indication of the origin of the ingredients,' 'hand sanitizer,' and 'table dividers' were not investigated in previous studies [41]. Among them, 'hand sanitizer' and 'table dividers' are concerns that have arisen with COVID-19 and can be seen as new qualities that reflect the phenomena of the times.
Thus, due to COVID-19, layout, table settings, cleanliness [42]; plexiglass partitions, hand disinfection, staff wearing disposable gloves, staff wearing protective masks or visors, disinfection of tables, cashless payment availability, disinfection of payment terminals [43]; restaurant dining environment, communication, hygiene, contactless features [44]; catering safety management, employee hygiene management, catering service, food quality, environmental atmosphere, and corporate social responsibility [45] have appeared as factors influencing customer perceptions of food-service. Similarly, in this study, hand sanitizer and plexiglass parts (table dividers) appeared, and hygiene and safety were mentioned. The in-depth, qualitative research conducted here allowed 'hand sanitizer' and 'table dividers' to be derived as quality factors affecting institutional foodservice during COVID-19 [21].

Study 2 3.2.1. Demographic Characteristics and Usage of Participants
For the survey, 464 (recovery rate 95.3%) questionnaires were collected after excluding those with missing or incomplete data. The demographic characteristics of the participants and the status of their institutional foodservice usage are shown in Table 7. This study population comprised 252 men (54.3%) and 212 women (45.7%), 296 of whom were married (63.8%), and 168 of whom were unmarried (36.2%). Among the participants, the largest proportions were 30-39 years old (38.4%), university graduates (51.5%), and office workers (44.6%), and they had an average monthly income of KRW 2 million to less than KRW 3 million (42.7%).
In institutional foodservice usage, more than 10 years (28.9%), more than 5 times a week (54.3%), once a day (65.3%), lunch (60.1%), and 3-5 min (55.6%) walk time to the staff restaurants was the highest. In addition, the highest response was that the meal price was unknown (46.8%) because company pay for the meal, followed by 4000-5000 won and 5000-6000 won. The meal payment was in the order of the company (66.2%), individual (28.2%), and company-individual share burden (5.6%).

Analysis of Institutional Foodservice Quality Attributes with the Kano Model
Customer satisfaction factors are based on customer perception of quality [31]. To identify the quality attributes important in institutional foodservice, the data from Study 1 were classified using a Kano evaluation table and CS. The quality factors of institutional foodservice were classified having the Attractive (A), One-dimensional (O), and Combination (C) attribute, as shown in Table 8. In the service category, 'no menu change' was found to have the C attribute of 1.9%, as a mix of I and A attributes. 'Adjustable Food quantity, special menu and events, and satisfaction survey and reflection of opinions' were found to have the A attribute, and 'friendly staff' had the O attribute. 'Close proximity to the restaurant and cheap meal prices' had the A attribute, and 'short wait time' had the O attribute.
In the safety category, 'fresh ingredients and good quality ingredients' had the O attribute, and 'indication of ingredient origin' had a CS of 5.6%,with the C attribute as a mixture of the O and A attributes. 'Hand sanitizer, staff hygiene, clean tableware, clean table and clean tableware return station' had the O attribute. 'Hand washing station, distance between seats, and table dividers' had the A attribute, and 'temperature regulation' was an O attribute.

Analysis of Satisfaction Factors with CSC
In the Kano model, the attributes of quality are determined using the highest responses. However, if there is no difference in frequency between the highest responses and the second responses, it is difficult to evaluate customer satisfaction using only the Kano model because the attribute of the second response is ignored.
Therefore, CSC were analyzed to identify the qualities that affect customer satisfaction and increase the reliability of the results [46][47][48]. The CSC of institutional foodservice was based on responses classified in the Kano model as having the A, O, M, I attributes, and the results are shown in Table 9. In Better (satisfaction coefficient), favorite menu (0.892) was the highest, followed by taste of food (0.875), special menu and events (0.868), short wait time (0.867), and close proximity to restaurant (0.853). In Worse (dissatisfaction coefficient), clean tableware (−0.886) was the most important, followed by clean tables (−0.847), staff hygiene (−0.767), fresh ingredients (−0.753), and taste of food (−0.700).
To increase customer satisfaction, it is obviously important to strengthen and maintain high quality in the categories that strongly affect the Better (satisfaction coefficient). However, because high Worse (dissatisfaction coefficient) scores negatively affect customer satisfaction, it is also important to improve Worse [38,46]. Among the attributes with high dissatisfaction coefficients, the top 12 were all O attribute, e.g., customers are satisfied if the tableware is clean and dissatisfied if it is not. Furthermore, the three attributes with the highest Worse are all in the hygiene category, indicating the importance of maintaining excellent hygiene. 'Taste of food' was ranked in the top two in Better and the top five in Worse and had an important influence on satisfaction. Therefore, 'taste of food' is an important quality to be managed.
The CSC is an effective way to categorize customer satisfaction factors because it can contribute to strategic decision-making about qualities to be improved and uses a distribution of continuous coefficients of Better and Worse rather than frequency [46][47][48]. Figure 4 shows the CSC Better (right) and Worse (left) for each institutional foodservice quality factor. The closer is the Better value is to 1, the greater the potential to increase customer satisfaction by improving or satisfying that characteristic. The closer a Worse value is to −1, the greater the potential to decrease customer satisfaction by failing to maintain or satisfy that characteristic.
To increase customer satisfaction, it is obviously important to strengthen and maintain high quality in the categories that strongly affect the Better (satisfaction coefficient). However, because high Worse (dissatisfaction coefficient) scores negatively affect customer satisfaction, it is also important to improve Worse [38,46].
Among the attributes with high dissatisfaction coefficients, the top 12 were all O attribute, e.g., customers are satisfied if the tableware is clean and dissatisfied if it is not. Furthermore, the three attributes with the highest Worse are all in the hygiene category, indicating the importance of maintaining excellent hygiene. 'Taste of food' was ranked in the top two in Better and the top five in Worse and had an important influence on satisfaction. Therefore, 'taste of food' is an important quality to be managed.
The CSC is an effective way to categorize customer satisfaction factors because it can contribute to strategic decision-making about qualities to be improved and uses a distribution of continuous coefficients of Better and Worse rather than frequency [46][47][48]. Figure  4 shows the CSC Better (right) and Worse (left) for each institutional foodservice quality factor. The closer is the Better value is to 1, the greater the potential to increase customer satisfaction by improving or satisfying that characteristic. The closer a Worse value is to −1, the greater the potential to decrease customer satisfaction by failing to maintain or satisfy that characteristic.

Importance-Satisfaction Analysis (ISA)
The Kano model can connect customer satisfaction factors with quality attributes, but it has limitations in analyzing how customer evaluate each quality attribute and indicating priorities for an improvement plan. Therefore, an ISA was conducted to provide that information.
First, a reliability analysis was performed to assess the internal consistency of the ISA questionnaire responses. As a result of calculating Cronbach's α, as shown in Table 10, importance at 0.951, satisfaction at 0.961, and importance and satisfaction by category were all higher than 0.7. Paired t-test was performed to verify the difference between importance and satisfaction of institutional foodservice quality factors. As shown in Figure 5, satisfaction was lower than importance in all questions (t = 12.701, p < 0.001), and importance and satisfaction differed significantly from each other.
priorities for an improvement plan. Therefore, an ISA was conducted to provide that information.
First, a reliability analysis was performed to assess the internal consistency of the ISA questionnaire responses. As a result of calculating Cronbach's α, as shown in Table 10, importance at 0.951, satisfaction at 0.961, and importance and satisfaction by category were all higher than 0.7. Paired t-test was performed to verify the difference between importance and satisfaction of institutional foodservice quality factors. As shown in Figure 5, satisfaction was lower than importance in all questions (t = 12.701, p < 0.001), and importance and satisfaction differed significantly from each other. In these results, 'taste of food' had a 16.000 difference in t-value compared with the other quality factors for foodservice, showing the largest difference between importance and satisfaction. The t-value was positive (+), indicating that satisfaction was lower than Satisfaction, * p < 0.05, ** p < 0.01, *** p < 0.001.
In these results, 'taste of food' had a 16.000 difference in t-value compared with the other quality factors for foodservice, showing the largest difference between importance and satisfaction. The t-value was positive (+), indicating that satisfaction was lower than importance. In 'close proximity to the restaurant', the difference in the t-value was 2.273, which was the smallest difference between importance and satisfaction. In other words, because 'taste of food' has a lower satisfaction value than importance value, it is important to manage the 'taste of food', and as shown in Table 7, it is considered that the difference between importance and satisfaction is small because the walk time is short (1 to 10 m).
The ISA was conducted to identify the improvement priorities for institutional foodservice. As shown in Figure 6, the qualities with the highest improvement priority (concentrate management here) were 'harmonious menu composition' and 'food temperature'. because 'taste of food' has a lower satisfaction value than importance value, it is important to manage the 'taste of food', and as shown in Table 7, it is considered that the difference between importance and satisfaction is small because the walk time is short (1 to 10 m).
The ISA was conducted to identify the improvement priorities for institutional foodservice. As shown in Figure 6, the qualities with the highest improvement priority (concentrate management here) were 'harmonious menu composition' and 'food temperature'.      First, 'harmonious menu composition' and 'food temperature' are the most important priorities (Concentrate management here), and they have the C (O/A) and O attribute, respectively. The commonality between the two qualities is that satisfaction when conditions are met, so satisfying harmonious menu composition and food temperature is an important way to increase customer satisfaction. Therefore, preparers should pay attention to ingredients, recipes, and agreement among side dishes and work to keep warm foods warm and cold foods cold.
The 'keep up the good work' quadrant contains attributes with both high importance and high satisfaction. Most of the qualities in this quadrant have O attribute, so it is important to maintain and manage satisfaction. First, 'harmonious menu composition' and 'food temperature' are the most important priorities (Concentrate management here), and they have the C (O/A) and O attribute, respectively. The commonality between the two qualities is that satisfaction when conditions are met, so satisfying harmonious menu composition and food temperature is an important way to increase customer satisfaction. Therefore, preparers should pay attention to ingredients, recipes, and agreement among side dishes and work to keep warm foods warm and cold foods cold.
The 'keep up the good work' quadrant contains attributes with both high importance and high satisfaction. Most of the qualities in this quadrant have O attribute, so it is important to maintain and manage satisfaction.
The 'low priority for managers' quadrant contains attributes with low importance and satisfaction. All of those factors, except indication of ingredient origin (C:O/A), had the A attribute. 'Indication of ingredient origin' is considered a low priority for managers because it must be well complied by legalities. On the other hand,  The 'low priority for managers' quadrant contains attributes with low importance and satisfaction. All of those factors, except indication of ingredient origin (C:O/A), had the A attribute. 'Indication of ingredient origin' is considered a low priority for managers because it must be well complied by legalities. On the other hand, table dividers have already been installed in most restaurants because of COVID-19. However, even if table dividers are installed, people can be uncomfortable sitting close together, and even if table dividers are not installed, people might be comfortable sitting in a zigzag or in only one direction. Therefore, the satisfaction with the table dividers was low, which is why it is placed in the low priority for managers quadrant. In addition, 'special menu and events' and 'satisfaction survey and reflection of opinion' have the A attribute, but they are in this quadrant because they are implemented only on special day or specific day.
The qualities distributed in the 'possible overkill' quadrant have high satisfaction but low importance. These qualities were no menu change (C:I/A), adjustable food quantity (A), close proximity to the restaurant (A), cheap meal prices (A), and hand sanitizer (O). These qualities reflect the general characteristics of institutional foodservice, and satisfaction with these qualities is generally high. Institutional foodservice is buffet-style restaurant that can control the amount of food autonomously. Additionally, it is close to work place, and meal price is cheap, and satisfaction of hand sanitizer provided at the entrance and inside the restaurant due to COVID-19 was high. In other words, it is considered to be distributed in 'Possible overkill' due to the high satisfaction of these qualities.
In addition to identifying the attributes of each quality, the Kano-ISA model has the advantage of simultaneously analyzing importance, satisfaction, and priority for improvement. When satisfaction is lower than importance, the qualities appear in the 'Concentrate management here' quadrant for urgent improvement. The qualities distributed in 'Keep up the good work' and 'Possible overkill' can be maintained in their current state because satisfaction is higher than importance. The qualities distributed in the 'Lower priority for managers' quadrant have low importance and satisfaction, but improving satisfaction is still important.

Discussion
Due to COVID-19, consumers not only want nutritious food, but are also concerned about safety [49,50]. Therefore, when dining out, customers prefer a place with good preventive measures, such as table dividers to prevent splashing during meals and good ventilation [13]. Checking customer's body temperature with a thermal imaging detector at the entrance of a restaurant [51,52], recording entry with a QR code [53], and providing hand sanitizer dispensers in the restaurant are now commonplace [12,53].
Among those changes, it was necessary to newly identify the factors that affect customer satisfaction with institutional foodservice on a daily basis. Therefore, a mixedmethods design was used here to comprehensively analyze the customer satisfaction factors in institutional foodservice from a user-based approach.
First, qualities were derived from in-depth interviews and open coding, which are qualitative user-based research methods to identify customer satisfaction factors. Most of those results were consistent with the customer satisfaction factors in previous studies [41], but 'indication of ingredient origin', 'hand sanitizer', and 'table dividers' were new quality factors. Among them, 'hand sanitizer' and 'table dividers' are considered to reflect changes in institutional foodservice that have emerged amid the COVID-19 pandemic.
Hand sanitizer and table dividers have been installed for customer safety during the pandemic, but they are now essentials for restaurant meals, and it is predicted that they will remain basic items in institutional foodservice.
The Kano model showed that the quality of institutional foodservice can be judged in terms of Attractive quality, One-dimensional, and Combination attributes. The CSC analysis showed that favorite menu, taste of food, and special menu and events had the highest satisfaction coefficients (Better), and clean tableware, clean table, and staff hygiene had the highest dissatisfaction coefficients (Worse). In the ISA, qualities for satisfaction being lower than importance (harmonious menu composition and food temperature) were distributed in the concentrate management here quadrant. In other words, to increase customer satisfaction with institutional foodservice, it is important to improve harmonious menu composition and food temperature.
On the other hand, due to the COVID-19, restaurants are recognized as dangerous area because of the high density of people gathering in one place [54]. Compared with the number of customers using institutional foodservice, the space for providing meals is small, and most customers use the space at specific time, so it is crowded. Therefore, to minimize the COVID risk in institutional foodservice spaces, customers can be asked to eat in a specific time interval, space between users and seats can be maximized, table dividers (partitions) can be installed, and customers can be asked to stay apart when returning tableware.
Studies related to dining out during the COVID-19 pandemic have shown that customers are willing to visit and higher costs at restaurants that have plexiglass dividers, air filters, and widely spaced tables and maintain preventive measures such as wearing masks while working [13]. Therefore, when designing a new restaurant for employees, it is im-portant to include a hand washing area, thermal image detector, table dividers (partitions), proper seating distance, and ventilation so that employees can safe and sanitary meals.
COVID-19 has increased customer interest in food hygiene and safety. Institutional foodservice in Korea is mainly operated as a face-to-face, self-service buffet. However, due to COVID-19, kiosks have been introduced, and menu selection and payment are expanding to non-face-to-face methods. Recently, robots that move cutlery or side dishes to a serving table have been introduced. It is thought that the hygiene and safety of institutional foodservice will continue to develop through the introduction of new nonface-to-face services.
Although the COVID-19 pandemic is not over, the changes to foodservice it has caused are expected to continue even after the pandemic has ended. Therefore, institutional foodservice should remain focused on the taste of meals and service and take care to establish a safe environment in terms of hygiene, cleanliness, and facilities.

Conclusions
In Korea, it is estimated that 36.7% of workers use institutional foodservice. During the COVID-19 pandemic, it has been difficult to use foodservice because it has been repeatedly opened and closed by pandemic-related lockdowns [55] and concerns about use [56]. During this study period (8 September-28 December 2020), social distancing was eased from stage 2 to stage 1 and then upgraded to stage 1.5 in November and stage 2.5 in December. As the regulations related to the use of food and beverage facilities changed according to the current status of the pandemic [57], it is believed that participants changed their perceptions of the quality of institutional foodservices.
This study supplemented the shortcomings of both qualitative and quantitative research by using a mixed-methods design. First, customer satisfaction factors were derived through in-depth interviews and open coding. Then, quantitative research was conducted and analyzed using the Kano model, CSC, and ISA. The quality attributes of institutional foodservice derived from the qualitative research were analyzed using the Kano model. The factors affecting customer satisfaction and dissatisfaction were analyzed using CSC, and the improvement priority factors were found through an ISA and presented using a Kano-ISA model. Therefore, this study is meaningful because it comprehensively analyzes the factors that affect customer satisfaction by analyzing them from various angles and presenting improvement priorities for foodservice operators.
This study has the following limitations. First, only 12 participants provided in-depth interviews, which limited the ability to collect various opinions. It would be meaningful to conduct in-depth interviews from more participants and compare the results according to the number of participants.
Second, institutional foodservice is characterized by the continuous provision of services to the same users under established conditions and standards. However, this study was conducted at a specific study point and could not examine changes in quality attributes over time. If a long-term longitudinal study had beed conducted, the life cycle of quality attributes in the Kano model would have evaluated [32].
Third, this study was conducted throughout institutional foodservice. It is also important to analyze and compare differences within institutional foodservice facilities by classifying them into manufacturing, distribution and services, government offices, and financial institutions. Such a facility-specific analysis could allow the needs of customers to be further satisfied by customizing services by facility type.
The environment of institutional foodservice changes over time. Because new qualities can arise and disappear as situations and users change, it is important to continue to pay attention to and work toward customer satisfaction.